Today's mobile networks were originally optimized for voice traffic. To carry large amounts of data traffic quickly and cost-effectively, improved radio interfaces—capable of providing higher-bandwidth connections to more users simultaneously—were needed. Hence, optimization of wideband radio technology was conceived for multimedia services and high-speed Internet access.
3G (Third Generation) wireless systems utilize wideband radio technology to provide global mobility with a wide range of services including telephony, paging, messaging, location tracking, and Internet and broadband data transfer. The International Telecommunication Union (ITU) has started the process of defining standards for third generation systems, referred to as International Mobile Telecommunications 2000 (IMT-2000). IMT-2000 includes systems such as CDMA-2000, UWC-136, DECT and UMTS. IMT-2000 ITU Standard Q.1701, Framework for IMT-2000 Networks was published in March of 1999 and may be found at www.itu.int/rec/recomendation.asp. IMT-2000 Supplemental ITU Standard Q.Sup30, Framework for IMT-2000 Networks—Roadmap to IMT-2000 Recommendations, Standards and Technical Specifications was published in December of 2000 and may also be found at www.itu.int/rec/recomendation.asp.
UMTS (Universal Mobile Telecommunications System) is a 3G broadband, packet-based communication of text, digitized voice, video, and multimedia at data rates up to and possibly higher than 2 megabits per second (Mbps), offering a consistent set of services to mobile computer and phone users no matter where they are located in the world. In UMTS, both connection-oriented and connectionless services are offered for Point-to-Point and Point-to-Multipoint communication. It is observed that once UMTS is fully implemented in many parts of the world, computer and phone users will be able to constantly communicate to the Internet as they travel (i.e., as they roam) and the users will have the same set of communication capabilities no matter where they travel. Through UMTS, users can have access through a combination of terrestrial wireless and satellite transmissions. The following data rates may be offered for wireless communication in UMTS: 144 kbps (kilobits per second) for satellite and rural outdoor communication, 384 kbps for urban outdoor communication, and 2048 kbps (2 Mbps) for indoor and low range outdoor communication. Newly defined enhancements to the standard (HSDPA, MIMO) enable data rates up to 10 Mbps or even 20 Mbps.
Today's cellular telephone systems are mainly circuit-switched, with connections always dependent on circuit availability. Circuit switching is a method of communication in which a dedicated communications path is established between two devices through one or more intermediate switching nodes. Packet switching, on the other hand, is a communication method in which packets of data are sent from one device to the other, over a number of communications paths—i.e., without a single, dedicated communications path. In circuit switching, unlike packet switching, digital data are sent as a continuous stream of bits.